Neutralization of Lipocalin-2 Diminishes Stroke-Reperfusion Injury

Guona Wang,Yu-Li Liu,Yi-Chinn Weng,Yu-Ting Huang,Cheng-Yuan Kao,Wen-Hai Chou,Tsong-Hai Lee,Yi-Chun Chen,I-Chen Chiang,Yi-Chu Liao

doi:10.3390/ijms21176253

Abstract

Oxidative stress is a key contributor to the pathogenesis of stroke-reperfusion injury. Neuroinflammatory peptides released after ischemic stroke mediate reperfusion injury. Previous studies, including ours, have shown that lipocalin-2 (LCN2) is secreted in response to cerebral ischemia to promote reperfusion injury. Genetic deletion of LCN2 significantly reduces brain injury after stroke, suggesting that LCN2 is a mediator of reperfusion injury and a potential therapeutic target. Immunotherapy has the potential to harness neuroinflammatory responses and provides neuroprotection against stroke. Here we report that LCN2 was induced on the inner surface of cerebral endothelial cells, neutrophils, and astrocytes that gatekeep the blood–brain barrier (BBB) after stroke. LCN2 monoclonal antibody (mAb) specifically targeted LCN2 in vitro and in vivo, attenuating the induction of LCN2 and pro-inflammatory mediators (iNOS, IL-6, CCL2, and CCL9) after stroke. Administration of LCN2 mAb at 4 h after stroke significantly reduced neurological deficits, cerebral infarction, edema, BBB leakage, and infiltration of neutrophils. The binding epitope of LCN2 mAb was mapped to the β3 and β4 strands, which are responsible for maintaining the integrity of LCN2 cup-shaped structure. These data indicate that LCN2 can be pharmacologically targeted using a specific mAb to reduce reperfusion injury after stroke.

Highlights

Ischemic stroke is a leading cause of mortality and adult disability worldwide [1]
Neutrophils are the first surge of blood cells that arrive at ischemic brain tissues, and contribute to oxidative stress, breakdown of the blood–brain barrier (BBB), cerebral edema, and brain injury [8,9]
Infiltration of neutrophils following ischemic stroke contributes to the disruption of the BBB

Summary

Introduction

Ischemic stroke is a leading cause of mortality and adult disability worldwide [1]. Thrombolysis with intravenous tissue plasminogen activator (tPA) and mechanical thrombectomy are the only procedures approved by the FDA to treat acute ischemic stroke [2]. Thrombectomy can be performed up to 24 h after symptom onset, but is intended for ischemic strokes caused by a large-vessel occlusion and can only be operated in stroke centers with sufficient resources and expertise [3]. Due to these limitations, it is estimated that less than 10% of stroke patients benefit from thrombolytic therapy [4]. Restoring cerebral blood flow is the goal of thrombolytic therapy, reperfusion itself may lead to the formation of cytotoxic reactive oxygen species (ROS), infiltration of peripheral immune cells, intense inflammatory responses, hemorrhagic transformation, and exacerbated cerebral infarction [5,6,7]. Migration of neutrophils from the bloodstream across the vascular endothelium to ischemic brain tissues is mediated by the local release of ROS, chemokines, and cytokines from the BBB

Methods

Results

Conclusion